Plumbing Vent Boot Flashing Repair: Method 2

The rubber collar on plumbing vent boot flashings don’t seem like they’re made to last as long as today’s long-lived asphalt roof shingles. I’ve had two collars split in the past 3 years on homes I built about 20 years ago. One presented itself as a stain on a ceiling and the other I found just by chance when spraying lichen and moss killer on a roof.

One solution for a split boot flashing is to remove and replace it with a new one. That involves stripping back shingles and runs the risk of damaging the shingles. Plus it takes an hour or more.   In less than half the time a repair can be made that will last as long as a full replacement and may actually be more durable. There are several repair methods. This blog will cover a repair using Perma-Boot repair flashing kit. See other blogs for a repair using uncured EPDM flashing tape and a new boot flashing, and a repair using a boot flashing with the roof pan trimmed off.

Perma-Boot is a pre-formed vent pipe repair flashing system that covers the existing pipe and boot flashing and only takes about 10 minutes to install. The base piece is made of two pieces of TPO plastic hinged together to accommodate roof slopes from 3/12 to 12/12 and vent pipe lengths from 9 in. to 13-1/2 in..

I modify the installation a little by separating the two pieces at the hinge and apply a bead of sealant around the dome of the lower piece. Then after dropping it over the vent pipe I snap the upper piece back over the hinge points. Chances are no water can be blown between the two parts of the base but I feel a little better with the sealant.

The top of the base piece slides over the vent pipe and is held in place by friction.

For added wind resistance in high wind areas a bead of sealant can be run around the rim of the lower piece and vent pipe before the upper piece is slid over the top.

Though I didn’t do it on this repair, the same extra step of sealing the vent pipe to the old flashing pan I used in the other flashing boot repair can be employed before installing Perma-Boot.

Perma-Boot is stocked at national roofing material wholesalers and big box retailers and costs around $20

(c) Michael R Guertin, Inc

Fine Homebuilding Recommended Products

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Flashing Boot

Adequately seal vulnerable vent penetrations through the roof with this galvanized flashing and flexible rubber collar.

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Cutting asphalt shingles is made faster, easier, and safer when using a hook-blade. Suitable for any standard utility knife, these are a must-have on any roofing project.

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Flashing Boot Repair

Prolonged exposure to the sun and weather can compromise the rubber gasket on standard vent flashing. Use this to quickly and permanently fix failed seals or to help protect the gasket in new-construction applications.

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